3rd-Degree Atrioventricular Block

Audience This oral boards case is appropriate for emergency medicine residents and medical students on emergency medicine rotations Introduction/Background Third-degree heart block (also known as complete heart block) is a cardiovascular emergency that requires prompt recognition. Complete heart block is a type of atrioventricular (AV) block whereby no atrial impulses reach the ventricular conduction system. The most common etiology of AV block is ischemic heart disease, with up to 1 in 5 patients developing some type of conduction disturbance after an MI.1 Complete heart block is seen in 8% of patients post-MI.2 Other causes include myocarditis, infectious endocarditis, infiltrative cardiac disease, congenital AV blocks, non-ischemic cardiomyopathy, electrolyte disturbances, and drug side effects.3 In complete heart block, the heart rate is dependent on the location of the block and a functioning secondary pacemaker within the conduction system. Analysis of the EKG will determine the location of this escape rhythm. For escape rhythms originating at the AV node or high in the His-Purkinje system, the QRS complex will typically be narrow, and the ventricular rate typically in the 40–60 bpm range. For blocks with ventricular escape rhythms, the QRS will appear wide, with rates of 20–40 bpm. Patients presenting with 3rd-degree AVB with ventricular escape rhythms can destabilize. If no escape rhythm generates, patients develop asystole and cardiac arrest. Since 1 in 600 adults over the age of 65 will develop a form of supraventricular conduction abnormality each year, this disease process is important to identify and treat.4 Effective management includes accurate interpretation of a 12-lead EKG, assessment of hemodynamic stability and systemic perfusion, and time-sensitive pharmacologic or procedural intervention. Educational Objectives At the end of this oral board session, examinees will: 1) demonstrate ability to obtain a complete medical history including detailed cardiac history, 2) demonstrate the ability to perform a detailed physical examination in a patient with cardiac complaints, 3) investigate the broad differential diagnoses which include acute coronary syndrome (ACS), electrolyte imbalances, pulmonary embolism, cerebrovascular accident, aortic dissection and arrhythmias, 4) obtain and interpret the cardiac monitor rhythm strip to identify complete heart block, 5) list the appropriate laboratory and imaging studies to differentiate arrhythmia from other diagnoses (complete blood count, comprehensive metabolic panel, magnesium level, EKG, troponin level, chest radiograph), 6) identify a patient with complete heart block and manage appropriately (administer IV atropine, attempt transcutaneous pacing, place a transvenous pacemaker, emergent consultation with interventional cardiology), 7) provide appropriate disposition to intensive care after consultation with interventional cardiologist. Educational Methods This is a straight-forward case which was written to assess learners’ ability to rapidly recognize an unstable cardiac rhythm and to subsequently treat and stabilize the patient. Oral board testing is used as a proxy for the emergency department (ED) and can assist with periodic assessment of resident performance while in the ED. We have found that oral board testing is a useful tool to assess residents’ critical thinking while still applying pressure that is needed to pass the examination itself. Large groups of residents can be assessed in a short time period without needing to “wait” for a particular clinical condition to present to the ED. In this case, learners were assessed using a free online evaluation tool, ie, Google forms. Multiple questions were written for each critical action, and the Google form served as the online evaluation and repository. The critical actions of the case were then tied to Emergency Medicine Milestones, and the results were compiled for use during residency clinical competency evaluations. Residents were provided with immediate verbal feedback of their performance and were also given their electronic evaluations when requested. Research Methods Learners and instructors were given the opportunity to provide electronic feedback after the case was completed to assess strengths and weaknesses, and subsequent modifications were made. Additionally, learners answered written multiple-choice questions after the case to assess for retention of the material. Results Senior learners found this to be a more enjoyable way to refresh their skills than direct lecture. Junior residents and students who encountered this clinical entity first in the oral board rather than in the ED, stated that they enjoyed the ability to “trial run” the case before being faced with an emergent and uncontrolled setting of the ED. Overall, the learners rated the case as 4.7 (1–5 Likert scale, 5 being excellent) after the mock oral board examination was completed. Discussion Students and residents who were assessed with a mock oral board session found this to be an improvement over traditional “lecture” and were pleased to have participated. The content is highly relevant to emergency medicine and the format forces learners to be actively engaged in review of the material. The case is a good model for the high stakes testing of written and oral board examinations, and is an effective way to assess a resident’s ability to rapidly assess and manage a life-threatening condition in the ED. Topics Third-degree AV block, complete heart block, 3rd-degree block, hypotension, syncope, bradycardia, cardiovascular emergency.

cerebrovascular accident, aortic dissection and arrhythmias, 4) obtain and interpret the cardiac monitor rhythm strip to identify complete heart block, 5) list the appropriate laboratory and imaging studies to differentiate arrhythmia from other diagnoses (complete blood count, comprehensive metabolic panel, magnesium level, EKG, troponin level, chest radiograph), 6) identify a patient with complete heart block and manage appropriately (administer IV atropine, attempt transcutaneous pacing, place a transvenous pacemaker, emergent consultation with interventional cardiology), 7) provide appropriate disposition to intensive care after consultation with interventional cardiologist.
Educational Methods: This is a straight-forward case which was written to assess learners' ability to rapidly recognize an unstable cardiac rhythm and to subsequently treat and stabilize the patient.Oral board testing is used as a proxy for the emergency department (ED) and can assist with periodic assessment of resident performance while in the ED.
We have found that oral board testing is a useful tool to assess residents' critical thinking while still applying pressure that is needed to pass the examination itself.Large groups of residents can be assessed in a short time period without needing to "wait" for a particular clinical condition to present to the ED.
In this case, learners were assessed using a free online evaluation tool, ie, Google forms.Multiple questions were written for each critical action, and the Google form served as the online evaluation and repository.The critical actions of the case were then tied to Emergency Medicine Milestones, and the results were compiled for use during residency clinical competency evaluations.Residents were provided with immediate verbal feedback of their performance and were also given their electronic evaluations when requested.
Research Methods: Learners and instructors were given the opportunity to provide electronic feedback after the case was completed to assess strengths and weaknesses, and subsequent modifications were made.Additionally, learners answered written multiple-choice questions after the case to assess for retention of the material.
Results: Senior learners found this to be a more enjoyable way to refresh their skills than direct lecture.Junior residents and students who encountered this clinical entity first in the oral board rather than in the ED, stated that they enjoyed the ability to "trial run" the case before being faced with an emergent and uncontrolled setting of the ED.Overall, the learners rated the case as 4.7 (1-5 Likert scale, 5 being excellent) after the mock oral board examination was completed.
Discussion: Students and residents who were assessed with a mock oral board session found this to be an improvement over traditional "lecture" and were pleased to have participated.The content is highly relevant to emergency medicine and the format forces learners to be actively engaged in review of the material.The case is a good model for the high stakes testing of written and oral board examinations, and is an effective way to assess a resident's ability to rapidly assess and manage a life-threatening condition in the ED.

Linked objectives and methods:
The learner in this case must be able to synthesize available history, physical examination and cardiac monitor findings (Objectives 1 and 2) in order to develop a broad differential of a patient who is in complete heart block (Objective 3).Without interpreting the cardiac monitor, the diagnosis may be missed if the learner does not identify the patient in complete heart block (Objective 3, 4 and 5).The oral board formatting allows the learner to interpret the rhythm strip in real-time in order to identify a life-threatening arrhythmia (Objective 4).The learner must be able to identify complete heart block and provide timely and appropriate treatment and disposition to prevent an adverse outcome (Objective 6 and 7).Debriefing of the case immediately afterward ensures assimilation of the sources of data to obtain the correct diagnosis and appropriate management of the case.

Recommended pre-reading for instructor:
• None, review references as needed

Results and tips for successful implementation:
This case was best used as an oral board examination.The learner should be directly observed by the examiner, either inperson or by video, and additional learners or instructors can also be present to observe.Learners were tested during emergency medicine conferences and during a mock oral board examination and oral board practice sessions.Assessment forms were created for the case using Google forms (http://docs.google.com/forms),and these were tied to Emergency Medicine Milestones (https://www.acgme.org/Portals/0/PDFs/Milestones/EmergencyMedicineMilestones.pdf?ver=2015-11-06-120531-877).Using this method, the oral board formatting could assess residents' clinical ability to practice in a non-threatening environment but also evaluate their progress along the ACGME's milestones.
It was a challenging case for medical students and interns, and tests the efficient, higher-level processing needed for senior residents.Fifty-five learners performed the examination and were evaluated.Most learners were able to obtain the diagnosis; however, there were some challenges in appropriate management of the case.The case was initially trialed with an electrolyte abnormality, ie, severe hypomagnesemia, though this caused too much additional time to treat and evaluate, was deemed not essential to the case, and was removed.
After a mock oral board session was completed, learners were given the ability to rate the cases individually, and this case scored 4.

Oral Case Summary
Diagnosis: 3rd-Degree (Complete) Heart Block Case Summary: This is a 58-year-old female patient with a previous history of hypertension and diabetes who presents to the emergency department after a syncopal episode.She is complaining of substernal chest pain upon arrival, stating that it is sharp and radiating to the right shoulder and has been present for around 24 hours.She thought it might be indigestion, but today she felt dizzy and fainted after getting up from the couch, which prompted her to activate EMS.She is initially bradycardic and hypotensive and should be brought into the resuscitation room upon arrival.
Order of Case: This is the case of a female patient presenting to the ED with syncope, who is found to have a 3rd-degree heart block.The diagnosis should be apparent via the initial rhythm-strip and/or EKG.The patient should immediately have transcutaneous pacing pads placed and preparations should be made for a transvenous pacemaker in the ED.If given, atropine will only temporarily correct the bradycardia, but will not affect the blood pressure, and again, is only temporary.If the initial rhythm is not recognized, the patient will deteriorate into symptomatic ventricular tachycardia, requiring the use of advanced cardiac life support (ACLS) resuscitation.Return of spontaneous circulation (ROSC) should be obtained and the 3rd-degree should again be recognized.Learners may intubate the patient at this point, which is acceptable, but is not the testable concept.Once the block is appreciated, the patient should be admitted to the intensive care unit, and interventional cardiology should be consulted to assess for permanent pacemaker placement.
If the learner does not appreciate the 3rd-degree block, ROSC can still be obtained, and the patient can still be admitted to the ICU.The case will not be passed, but the learner should be debriefed promptly and will be given the diagnosis and the appropriate EKG findings.

Reassesses after implementing a stabilizing intervention
ORAL BOARDS ASSESSMENT

Critical Actions: 1 .
Triage the patient to the resuscitation room 2. Request the patient be placed on the cardiac monitor, obtain a rhythm strip/EKG and interpret the findings 3. Place temporary transcutaneous pacemaker pads 4. Insert transvenous pacemaker Meloy P, et al. 3 rd -Degree Atrioventricular Block.JETem 2022.7(2):O1-28.https://doi.org/10.21980/J8NP9S 9 General appearance: Disheveled, mild-to-moderate distress Primary survey: • Airway: Intact • Breathing: Intact, tachypneic • Circulation: Intact peripheral pulses, hypotensive, bradycardic Physical examination: • General appearance: Disheveled, mild-to-moderate distress • Head, eyes, ears, nose and throat (HEENT): o Head: Within normal limits o Eyes: Within normal limits o Ears: Within normal limits o Nose: Within normal limits o Oropharynx/Throat: Within normal limits • Neck: No JVD, trachea midline • Chest: Tachypneic, lungs CTA bilaterally, no wheezes, crackles or rales • Cardiovascular: Bradycardic, irregular heart tones, no murmurs, 1+ radial and dorsalis pedis pulses bilaterally • Abdominal/GI: Within normal limits • Genitourinary: Deferred • Rectal: Within normal limits • Extremities: Trace pitting edema of the bilateral lower extremities, 2+ radial and dorsalis pulses bilaterally • Back: Within normal limits • Neuro: Within normal limits • Skin: Diaphoretic • Lymph: Within normal limits • Psych: Within normal limits Critical Actions: Triage the patient to the resuscitation room Request the patient be placed on the cardiac monitor, obtain a rhythm strip/EKG and interpret the findings Place temporary transcutaneous pacemaker pads Insert transvenous pacemaker Admit to intensive care unit with interventional cardiology consult Summative and formative comments: Obtain and interpret the cardiac monitor rhythm strip to identify complete heart block 5. List the appropriate laboratory and imaging studies to differentiate arrhythmia from other diagnoses (complete blood count, comprehensive metabolic panel, magnesium level, EKG, troponin level, chest radiograph) 6. Identify a patient with complete heart block and manage appropriately (administer IV atropine, attempt transcutaneous pacing, place a transvenous pacemaker, emergent consultation with interventional cardiology) 7. Provide appropriate disposition to intensive care after consultation with interventional cardiologist 8. concept in emergency medicine; we feel this case is an important addition to any written or oral board session.
7 (1-5 Likert scale, 5 being excellent).Learners stated that the oral board session was a "quick diagnosis but required me to think about how to investigate for underlying causes," and "hard to guess right off the bat, scary that I needed to resuscitate, but glad I finished the case."This is a highly testableTopics:Third-degree AV block, complete heart block, 3 rd -degree block, hypotension, syncope, bradycardia, cardiovascular emergency.Objectives:By the end of this oral boards case, examinees will be able to:1.Demonstrate ability to obtain a complete medical history including detailed cardiac history 2. Demonstrate the ability to perform a detailed physical examination in a patient with cardiac complaints 3. Investigate the broad differential diagnoses which include acute coronary syndrome (ACS), electrolyte imbalances, pulmonary embolism, cerebrovascular accident, aortic dissection and arrhythmias 4.

Did not achieve Level 1 Considers a list of potential diagnoses Considers an appropriate list of potential diagnosis May or may not make correct diagnosis Makes the appropriate diagnosis Considers other potential diagnoses, avoiding premature closure 5 Pharmacotherapy (PC5) Did not achieve Level 1 Asks patient for drug allergies Selects an appropriate medication for therapeutic intervention, considering potential adverse effects Selects the most appropriate medication(s) and understands mechanism of action, effect, and potential side effects Considers and recognizes drug-drug interactions 6 Observation and reassessment (PC6) Did not achieve Level 1 Reevaluates patient at least one time during the case Reevaluates patient after most therapeutic interventions Consistently evaluates the effectiveness of therapies at appropriate intervals ORAL BOARDS ASSESSMENT
Standardized assessment form for oral boards cases.JETem ã Developed by: Megan Osborn, MD, MHPE; Shannon Toohey, MD; Alisa Wray, MD Meloy P, et al. 3 rd -Degree Atrioventricular Block.JETem 2022.7(2):O1-28.https://doi.org/10.21980/J8NP9S 12 Standardized assessment form for oral boards cases.JETem ã Developed by: Megan Osborn, MD, MHPE; Shannon Toohey, MD; Alisa Wray, MD Meloy P, et al. 3 rd -Degree Atrioventricular Block.JETem 2022.7(2):O1-28.https://doi.org/10.21980/J8NP9S13

Nitrite Negative Blood Negative Microscopy White blood cells (WBC) Negative Red blood cells (RBC) Negative Squamous cells 5/hpf Bacteria 0-2/hpf Stimulus #9 Monitor Rhythm Strip
If unsuccessful in terminating block, temporize with transcutaneous or transvenous pacing and arrange for emergent hemodialysis. 103.For 3rd-degree AV-block due to beta blocker or calcium channel blocker overdose, administer IV Calcium (3g Calcium Gluconate via peripheral IV or 1 g Calcium Chloride via Central Line), 5 mg IV Glucagon bolus, and initiate IV Insulin infusion 1 unit/kg/hr with dextrose infusion.11 Image Citation: Author's own imageStimulus #11Repeat EKGImage Citation: Author's own image block recurrence.